I'm fairly new to chemistry, and I have a hard time understanding how chemical energy is stored in carbon (I'm aware that the question can be generalised to 'how is chemical energy stored', but I'm trying to understand it in the example of carbon). In the example in my book, carbon and oxygen react to form carbon dioxide, releasing energy in the form of warmth in the process.
My book says that the energy released in this process mainly comes from carbon, which is originally the solar energy stored by plants. I have tried to look for explanations how that energy is stored (not how the process of photosynthesis works, but in what form or what is the meaning of 'stored energy'), but I still can't really wrap my head around it. The best answer so far was What is the nature of chemical energy?
If I understand the answer there correctly, the bond potential energy of a carbon dioxide molecule is lower than the combined bond potential energy of a carbon atom and an oxygen molecule. Given that, there are still two things I don't understand:
- Why is the bond potential energy in the carbon atom and/or oxygen molecule higher than that of a dioxide molecule? How can that be explained? Is this directly related to the chemical traits of the elements carbon and oxygen and the compound carbon dioxide?
- Why, or better said how is said bond potential energy converted to warmth in the process?
I'm aware that there might be concepts in physics here I don't know or understand to understand a possible answer, and I would be thankful for any pointers to what subjects I should be first reading to understand such an answer.
Edit: I would like to quote here something I came across on Wikipedia. I'm not providing it as an answer nor claiming it is correct, just trying to illustrate how confusing it is to find a satisfying answer for this matter. This comes from https://en.wikipedia.org/wiki/Chemical_bond#Overview_of_main_types_of_chemical_bonds:
In the simplest view of a covalent bond, one or more electrons (often a pair of electrons) are drawn into the space between the two atomic nuclei. Energy is released by bond formation. This is not as a reduction in potential energy (sic), because the attraction of the two electrons to the two protons is offset by the electron-electron and proton-proton repulsions. Instead, the release of energy (and hence the stability of the bond) arises from the reduction in kinetic energy due to the electrons being in a more spatially distributed (i.e. longer de Broglie wavelength) orbital compared with each electron being confined closer to its respective nucleus.
Italic and bold added by me. Note that Wikipedia itself has a '[clarification needed]' tagging in the middle of that text, right after 'two protons', which I removed.
So if I understand that correctly and assuming that info is correct: any formation of a covalent bond would result in energy being released. But that still doesn't explain why my book is claiming the energy is particularly stored in carbon (and not in oxygen), and why it is released as warmth. In addition, the explanation on Wikipedia would contradict what I referred to earlier, namely that the energy released comes from differences in bond potential energy.